Commissioning for Radiotherapy TPS

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IAEA-TECDOC-1583

Commissioning of RadiotherapyTreatment Planning Systems:

Testing for Typical External Beam

Treatment TechniquesReport of the Coordinated Research Project (CRP) on

Development of Procedures for Quality Assurance ofDosimetry Calculations in Radiotherapy

January 2008


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IAEA-TECDOC-1583

Commissioning of RadiotherapyTreatment Planning Systems:

Testing for Typical External Beam

Treatment TechniquesReport of the Coordinated Research Project (CRP) on

Development of Procedures for Quality Assurance ofDosimetry Calculations in Radiotherapy

January 2008


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The originating Section of this publication in the IAEA was:

Dosimetry and Medical Radiation Physics SectionInternational Atomic Energy Agency

Wagramer Strasse 5P.O. Box 100

A-1400 Vienna, Austria

COMMISSIONING OF RADIOTHERAPY TREATMENT PLANNING SYSTEMS:TESTING FOR TYPICAL EXTERNAL BEAM TREATMENT TECHNIQUES

IAEA, VIENNA, 2008IAEA-TECDOC-1583

ISBN 9789201005083ISSN 10114289

IAEA, 2008

Printed by the IAEA in AustriaJanuary 2008


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FOREWORD

Quality Assurance (QA) in the radiation therapy treatment planning process is essential to

ensure accurate dose delivery to the patient and to minimize the possibility of accidental

exposure. Computerized radiotherapy treatment planning systems (RTPSs) are now widely

available in both industrialised and developing countries so, it is of special importance to

support hospitals in the IAEA Member States in developing procedures for acceptancetesting, commissioning and ongoing QA of their RTPSs. Responding to these needs, a group

of experts developed a comprehensive report, the IAEA Technical Reports Series No 430

Commissioning and quality assurance of computerized planning systems for radiation

treatment of cancer, that provides the general framework and describes a large number of

tests and procedures to be considered by the RTPS users.

To provide practical guidance for implementation of IAEA Technical Reports Series No. 430

in radiotherapy hospitals and particularly in those with limited resources, a coordinated

research project (CRP E2.40.13) Development of procedures for dosimetry calculation in

radiotherapy was established. The main goal of the project was to create a set of practical

acceptance and commissioning tests for dosimetry calculations in radiotherapy, defined in a

dedicated protocol. Two specific guidance publications that were developed in the frameworkof the Coordinated Research Project E2.40.13 are based on guidelines described in the IAEA

Technical Report Series No. 430 and provide a step-by-step description for users at hospitals

or cancer centres how to implement acceptance and commissioning procedures for their

RTPSs. The first publication, Specification and acceptance testing of radiotherapy treatment

planning systems IAEA-TECDOC-1540 uses the International Electrotechnical Commission

(IEC) standard IEC 62083 as its basis and addresses the procedures for specification and

acceptance testing of RTPSs to be used by both manufacturers and users at the hospitals.

Commissioning is one of the most important parts of the entire QA programme for both the

RTPS and the planning process. Commissioning involves testing of system functions,

documentation of the different capabilities and verification of the ability of the dosecalculation algorithms to reproduce measured dose calculations. The current report is limited

to treatment simulation tests for external high-energy photon beams that are performed prior

to clinical use of RTPS. The report deals with the verification of the dose calculations through

commissioning tests that cover typical treatment techniques only. This report also summarizes

the results of a pilot study of the clinical commissioning recommendations that was

performed by the participants of the Coordinated Research Project at their home institutions.

The summary of the pilot study is available to medical physicists as an example of the

implementation of the clinical commissioning procedures for RTPSs at their hospitals. Issues

related to intensity modulated radiation therapy (IMRT) or other specialized techniques such

as stereotactic radiosurgery are not addressed in this clinical commissioning report. While

recognizing the specific scope of this report, this publication is useful to the purchasers ofRTPSs in any country although they may have to perform tests beyond those described in this

report to meet the needs of specialized techniques that have not been addressed here.

The IAEA wishes to express its gratitude to all authors and reviewers of this publication as

listed at the end of the publication. The final editorial contribution of J. Van Dyk (Canada),

G. Ibbott (United States of America), R. Schmidt (Germany), and J. Welleweerd

(Netherlands) is gratefully acknowledged. The IAEA staff member responsible for the

preparation of this publication was S. Vatnitsky from the Division of Human Health.


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EDITORIAL NOTE

The use of particular designations of countries or territories does not imply any judgement by the

publisher, the IAEA, as to the legal status of such countries or territories, of their authorities and

institutions or of the delimitation of their boundaries.

The mention of names of specific companies or products (whether or not indicated as registered) does

not imply any intention to infringe proprietary rights, nor should it be construed as an endorsementor recommendation on the part of the IAEA.


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CONTENTS

1. INTRODUCTION .........................................................................................................................1

1.1 Background..........................................................................................................................11.2 Scope and purpose of the current report ..............................................................................11.3 Target audience....................................................................................................................21.4 How to use this report ..........................................................................................................2

2. CLINICAL COMMISSIONING TESTS .............................................................................................3

2.1. Introduction..........................................................................................................................32.2. Phantom for clinical commissioning tests ...........................................................................4

2.3. Description of clinical commissioning test cases ................................................................52.3.1. Anatomical and input test cases ..............................................................................62.3.2. Dosimetric test cases ...............................................................................................6

Case 1: Testing for reference condition based on CT data ..........................................6

Case 2: Oblique incidence, lack of scattering and tangential fields.............................6Case 3: Significant blocking of the field corners.........................................................6Case 4: Four field box..................................................................................................7

Case 5: Automatic expansion and customized blocking..............................................7Case 6: Oblique incidence with irregular field and

blocking the centre of the field...................................................................7Case 7: Three fields, two wedge-paired, asymmetric collimation ...............................7Case 8: Non coplanar beams and test of couch rotation

and collimator rotation...............................................................................7

APPENDIX A: CLINICAL TEST CASES RECOMMENDEDDURING COMMISSIONING.....................................................................................9

A.1 Anatomical and input test cases...........................................................................................9A.2. Dosimetric test cases..........................................................................................................12

APPENDIX B: RESULTS OF PILOT STUDY..................................................................................29

APPENDIX C: COMPARISON OF DIFFERENT PHANTOMS FORCLINICAL COMMISSIONING OF RTPS FOLLOWING

AN IAEA PROTOCOL .............................................................................................35

APPENDIX D: THE USE OF CLINICAL COMMISSIONING TEST RESULTSIN PERIODIC QUALITY ASSURANCE OF RTPS................................................43

APPENDIX E: BEAM SPECIFIC CALCULATION CHECKS........................................................49

REFERENCES.......................................................................................................................................59

GLOSSARY...........................................................................................................................................61

ABBREVIATIONS................................................................................................................................65

CONTRIBUTORS TO DRAFTING AND REVIEW............................................................................67


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1. INTRODUCTION1.1 BackgroundThe IAEA Technical Reports Series No. 430 [1] provides a general framework and describes

a large number of tests and procedures that should be considered by the users of RTPSs.

However, the workload for the implementation of the recommendations from TRS-430 isenormous and requires far more personnel and instrumentation resources than is available in

most facilities, particularly within smaller hospitals. These hospitals are not always able to

perform complete characterization, algorithm validation and software testing of dose

calculation algorithms used in RTPS. Dose computation verification is an important part of

acceptance testing and commissioning procedures and it was recognized that there is an

urgent need for a practical document describing a limited number of test cases, to be

performed by a user in a hospital, which can be carried out in a reasonable amount of time.

Such cases should help to avoid severe errors in the treatment planning process in a specific

institution. Reduction of extensive published quality assurance (QA) recommendations to a

QA program feasible in all hospitals can be achieved without loss of comprehensiveness by

appropriate and optimal division of effort during acceptance testing between the RTPS vendorand hospital staff.

To provide practical guidance for implementation of IAEA TRS-430 in radiotherapy hospitals

and particularly in those with limited resources, a coordinated research project (CRP

E2.40.13) Development of procedures for dosimetry calculation in radiotherapy was

established. The main goal of the project was to create a set of practical acceptance and

commissioning tests for dosimetry calculations in radiotherapy, defined in a dedicated

protocol. Two documents that were developed in the framework of the Coordinated Research

Project E2.40.13 are based on guidelines described in IAEA TRS-430 and provide a step-by-

step description for users at hospitals or cancer centres to implement acceptance and

commissioning procedures for RTPSs.

The first document Specification and acceptance testing of RTPS [2] uses the IEC 62083

standard [3] as its basis and serves as a protocol to be used by both manufacturers and users

for the specification and acceptance testing of RTPSs. Recommendations are provided in this

report for specific tests to be performed at the manufacturing facility type tests, and

acceptance tests to be performed at the users site site tests. The vendor performs factory

type tests using preloaded generic machine data and a preinstalled simple water phantom as a

tool for testing dosimetry calculations. Following the recommendations of this IAEA report

[2] the user will acquire the initial knowledge of the algorithms used in the system and verify

their accuracy. This will be done together with the vendor during the demonstration of the

RTPS performance for specific dosimetry calculation site tests. Using pre-installed beam data

the vendor will show the user that similar results can be obtained on-site compared to thefactory type tests results. After signing the acceptance document the user can move to the next

step commissioning to implement a RTPS into clinical practice.

1.2 Scope and purpose of the current reportCommissioning is one of the most important parts of the entire QA programme for both the

RTPS and the planning process. Commissioning involves testing of system functions,

documentation of the different capabilities and verification of the ability of the dose

calculation algorithms to reproduce measured dose calculations. The current document is

limited to treatment simulation tests for external high-energy photon beams that are

performed prior to clinical use of RTPS. The document deals with the verification of the dosecalculations through commissioning tests that cover typical treatment techniques only. The

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purpose of this testing is to confirm that the logistic chain starting from CT scanning,

anatomic modelling, treatment planning and monitor unit/time (MU/time) calculation is

operable for typical treatment techniques and leads to the desired results with sufficient

accuracy. Following TRS-430, the tests of RTPS for typical treatment techniques described in

the current document are defined as clinical commissioning tests.

During clinical commissioning tests the RTPS performance will be verified for typical

conventional and conformal radiotherapy techniques, including the comparison of dosecalculation results and measured values for an inhomogeneous anthropomorphic phantom,

and the MU/time calculation checks. The procedures for clinical commissioning tests

described in the document are based on the use of the CIRS phantom Model 002LFC that was

selected following specific study described in Appendix C. The phantom is equipped with a

set of certified electron density reference plugs that enable the verification of the CT

number/electron density conversion procedure. The tests are structured so that at first, the

dose distributions for single beams are considered, then standard multiple field techniques are

used, and finally complex multi-field arrangements are applied. These checks are primarily

aimed at confirming that the planned absolute doses delivered to the phantom agree with

those as determined by measurement.

Issues related to intensity modulated radiation therapy or other specialized techniques are not

addressed in the IAEA commissioning document. While recognizing the specific scope of the

document, users of RTPSs will find the report useful. However, they may have to perform

tests beyond those described in this report to meet the needs for the full range of clinical

techniques.

The clinical commissioning procedures were tested through a pilot study by the participants

of the IAEA CRP to ensure its recommendations are practical and can be performed in

reasonable time. The pilot study includes a comparison of test results that are grouped into

tabular form for different RTPS algorithms showing the observed range of deviations.

The results of RTPS commissioning can be used as the reference data for the ongoingperiodic QA programme that covers checks of the integrity of hardware, software and data

transfer. General procedures for Quality Control (QC) checks of RTPS are outlined in TRS

430 together with a reference to a test designed to perform that check, and a suggested

frequency for the test. The current report also provides specific recommendations on the

implementation of the results of clinical commissioning tests based on the use of the CIRS

phantom Model 002LFC into the practice of periodic QA for RTPS used in external

radiotherapy treatment planning. If another phantom was used for clinical commissioning

tests, the recommended procedure can be adjusted to the features of this phantom. The QC of

brachytherapy options and the re-commissioning after upgrades are outside of the scope of the

current report.

1.3 Target audienceThis report is aimed at all those individuals who participate in any aspect of RTPS

commissioning and QA. In general, such individuals are medical physicists with specialized

radiation oncology physics training and practical clinical experience. This report is especially

relevant to those individuals who have a major responsibility for the RTPSs in their

departments.

1.4 How to use this reportThis report is intended as a guide for testing RTPS calculations for typical treatmenttechniques and provides step-by-step instructions for these tasks. The clinical commissioning

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tests based on the use of the specified phantom should be completed according to the

recommendations described in Section 2 and Appendix A. If the institution is using treatment

techniques that are beyond the scope of this report, the set of clinical dose calculation-

commissioning tests should be extended (see TRS-430 for details).

This protocol was tested through a pilot study by the participants of the IAEA Coordinated

research project E2.40.13 and the test results are given in Appendix B for Co-60 and high-

energy photon beams, including a table with estimated time needed to perform each test. The

dose comparison results are given for different algorithms used in RTPSs to show the

observed ranges of deviations.

The characteristics of phantoms that can be used during clinical commissioning are discussed

in Appendix C.

The results of RTPS commissioning can be used as the reference data for the ongoing

periodic QA programme and Appendix D provides specific recommendations on the

implementation of the results of clinical commissioning tests into the practice of periodic QA

for RTPS used in external radiotherapy treatment planning.

If the results of clinical commissioning tests are outside of the acceptance testing tolerances,

the user should seek possible explanations for observed deviations. As a first step it is advised

to perform beam specific calculation checks as it is indicated in Appendix E. In case of

persisting deviations the user may consult the results of acceptance testing and contact the

manufacturer for advice.

2. CLINICAL COMMISSIONING TESTS

2.1. Introduction

Complete characterisation, algorithm validation and software testing of a dose calculation

algorithm used in RTPS are typically beyond the capabilities of most radiotherapy hospitals.

Therefore, this report proposes, in combination with the IAEA Report [2], a limited set of

tests, which will help an individual institution to prepare each photon dose calculation

algorithm used in an RTPS for routine clinical use. The user must define the treatment

capabilities which will be used, provide appropriate input data, perform beam fitting, acquire

a measured data set for RTPS testing and analyse results, then finally to take responsibility for

the verification of the dose calculation algorithm(s) which will be tested and then used

clinically.

Using the IAEA Report [2] the user will acquire the initial knowledge of the algorithms usedin the system and check their accuracy. The acceptance testing will be performed together

with the vendor using pre-installed beam data in order to show the user that the same results

can be obtained on-site compared to the factory type tests results.

After completion of acceptance testing a set of data measured following the manufacturer

specifications has to be entered into the system for beam fitting. This beam fitting procedure

must be validated by comparing the difference in measured and computed doses with

tolerance values given in Table 8 of IAEA Report [2]. Test conditions must include the

clinical range for open, irregular and wedged fields measured in a homogeneous water

phantom. It is mandatory that beam fitting and validation be done for every algorithm that

will be used clinically in the accepted RTPS.

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The general description of the clinical commissioning procedures are given below, but the

details and observed outcomes are presented in Appendixes A and B. The clinical

commissioning test cases are designed according to the typical treatment planning process. A

specific phantom should be used that can be applied for anatomical and dosimetric tests. The

anatomical tests are related to the creation of an anatomical model for the patients treatment

planning. The dosimetric tests are designed to cover a wide range of treatment techniques

applied in clinical practice. The details of the clinical commissioning tests are given inAppendix A. The dose comparison results are given in Appendix B for different algorithms

used in RTPSs to show the observed ranges of deviations between measured and calculated

doses.

2.2. Phantom for clinical commissioning tests

The features of phantoms suitable for clinical commissioning and QA of RTPS are suggested

in TRS-430 [1]. Several categories should be considered:

CT phantomo

Check of CT number to relative electron density (RED) conversiono Beam geometry assessmentso Digitally reconstructed radiograph (DRR) generationo Multiplanar reconstruction

Slab geometry phantomo Water/tissue equivalent materialo Possibility for film dosimetryo Check of corrections for inhomogeneous geometries

Anthropomorphic phantomo Dosimetric measurements of typical or special treatment techniques

The clinical commissioning tests described in this report are based on the use of CIRS Thoraxphantom Model 002LFC (see Figure 1). This phantom was chosen for clinical commissioning

tests, as it is commercially available and complies with the most of the requirements listed

above (see Appendix C for details). The use of other suitable phantoms for clinical

commissioning testing is possible, but it will require adaptation of test geometries and the

selection of the appropriate measurement points. The comparison of measured and calculated

data in these phantoms may also influence the range of observed deviations. The application

of several phantoms that can be used during clinical commissioning is discussed in

Appendix C.

The CIRS Thorax phantom is elliptical in shape and represents an average human torso in

proportion, density and two-dimensional structure. The phantom has a body made of plastic

water, lung and bone sections with holes to hold interchangeable rod inserts. Tissue

equivalent interchangeable rod inserts accommodate ionization chambers allowing point dosemeasurements in multiple planes within the phantom. The placement of holes allows

verification in the most critical areas of the chest. One half of the phantom is divided into 12

sections, each 1 cm thick, to support either radiographic or radiochromic films. Handling,

assembly and proper orientation of the phantom is provided with the use of an alignment base

and holding device. The phantom is completed with a set of four certified electron density

reference plugs (muscle, bone, lung and adipose equivalent tissue, see Table 1).

A cross mark is located on the top of the phantom, together with two additional lateral

markers to ease the phantom set-up. For each test the phantom is aligned with the help ofthese markers. The clinical commissioning measurements are performed with ionization

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chambers having a calibration traceable to a standards laboratory, placed into the

corresponding holes in the phantom.

Table 1 Certified density reference materials as included in the manual for the CIRS phantom

Density (g/cm3) Electron density

per cm3 x 1023

Electron density

relative to water

Lung 0.21 0.69 0.207Bone 1.60 5.03 1.506

Muscle 1.06 3.48 1.042Adipose 0.96 3.17 0.949

Plastic water(body)

1.04 3.35 1.003

Figure 1 Thorax Phantom (CIRS Model 002LFC).

2.3. Description of clinical commissioning test cases

Clinical commissioning test cases covering a wide range of typical clinical situations are

structured in such a way that dose distributions are first checked for single beams, then

standard multiple field techniques are used, and finally complex multi field arrangements are

applied. These tests are primarily aimed at confirming that the planned dose will be in

agreement with that determined by measurement. The dose calculations for each test are

performed for each available algorithm based on the grid size normally used in clinical

practice. A small volume ionization chamber is recommended for the measurements. The

chamber is placed in the corresponding plug, and this plug is fully inserted into the selectedhole of the phantom. All doses refer to absorbed dose to water regardless of the measurement

region of the phantom (lung, bone). During the measurements all empty holes should be filled

with supplied plugs of densities corresponding to the regions. The measurements will be

performed for each single beam and for all beams for multi-field techniques. The comparison

of measured and calculated dose values are to be reported in the corresponding tables of

Appendix A. As a part of the clinical commissioning process the user should perform

independent MU/time calculations for each single beam and compare the results with RTPS

calculated MUs/time values.

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2.3.1. Anatomical and input test casesThe anatomical and input test cases are designed so that they cover the process of creating a

patients model for treatment planning including the process of converting CT numbers to

relative electron densities. Furthermore the graphic input/output hardware is also checked.

Case 1: Verification of digitized contour non-dosimetric test

The purpose of this test is to verify the digitizing capabilities of the RTPS by comparing the

digitized master copy of the CIRS 002LFC Front view transverse cross-section contour

(provided by the manufacturer) with the printed copy produced by RTPS or with the

corresponding contour of the CIRS phantom created from CT images. This test covers input

tests 1 and 2 and anatomical test cases 1 to 4 from TRS-430.

Case 2: Verification/determination of CT numbers to relative electron density conversion in

the RTPS

The purpose of this test is to determine and, if needed, to adjust the CT number to RED

conversion curve used by the RTPS. The CIRS 002LFC phantom should be scanned in the

available CT scanner using the local scanning protocol and following the set-up given in

Figure A.2. This test covers the CT conversion test described in TRS-430 - section 9.2.9.

2.3.2. Dosimetric test casesThe purpose of each dosimetric test case is described below. As these cases are the subset of

the cases summarized in TRS 430, the correspondence to the tests in TRS-430 is also given.

Generally one dosimetric test case covers the check of several parameters. A detailed

instruction for performing the testing and evaluating the results is given in Appendix A. A

second CT scan of the phantom that will be used for dosimetric test calculations should bedone with all plugs inserted into the corresponding holes (Figure A.3).

Case 1: Testing for reference condition based on CT data

The purpose of this test is to verify the calculation for the reference field, based on relative

electron densities converted from CT data. A 10 cm x 10 cm field with a gantry angle of 0

and collimator angle of 0 is used. This test corresponds to photon test 1 and MU test 1 in

TRS 430.

Case 2: Oblique incidence, lack of scattering and tangential fields

The purpose of this test is to verify calculations in case of lack of scattering for the tangential

field. A 15 cm x 10 cm field with a wedge and a gantry angle of 90 and collimator angle

depending on the wedge orientation is used. This test corresponds to photon tests 7, 10 and

MU test 2 in TRS 430.

Case 3: Significant blocking of the field corners

The purpose of this test is to verify the calculation for the blocked field: a 14 cm x 14 cm field

with a collimator angle of 45 is blocked to a 10 cm x 10 cm field with standard blocks or

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with the multileaf collimator (MLC). This test corresponds to photon tests 1, 3 and MU test 4

in TRS 430.

Case 4: Four field box

This technique is used in many hospitals and the purpose of this test is to verify the

calculation of the dose delivered with separate beams and the total dose from four fields. Thistest corresponds to overall clinical test 1 in TRS-430.

Case 5: Automatic expansion and customized blocking

The purpose of this test is to verify the auto-aperture function of the RTPS and customized

blocking as well as the calculations with lung inhomogeneity. A cylinder of 8 cm diameter

and 8 cm length centered in point #2 should be expanded with a margin of 1 cm in all

directions using the expansion tools available. An MLC or block to conform to expanded

volume should be applied. This test combines test conditions related to beam test 8, photon

test 13, MU test 6, and clinical test 4 as described in TRS-430.

Case 6: Oblique incidence with irregular field and blocking the centre of the field

The purpose of this test is to verify the calculations for irregular fields with the blocking of

the centre of the field. A 20 cm x 10 cm field with gantry angle of 45 is used. An L-shaped

field should be created by blocking off a 6 cm x 12 cm portion of the field using a custom

block orMLC. This test corresponds to MU test 4 as described in TRS-430.

Case 7: Three fields, two wedge-paired, asymmetric collimation

The purpose of this test is to verify the calculations with wedge-paired fields and asymmetriccollimation (if asymmetric collimators are not available, half-beam block may be used). This

test corresponds to MU test 3 and overall clinical test 3 a described in TRS-430.

Case 8: Non coplanar beams and test of couch rotation and collimator rotation.

The purpose of this test is to verify the calculations with the couch and collimator rotations.

Three fields with different gantry angles and collimator rotations are used.

This test corresponds to beam tests 6, 12 and overall clinical test 6 in TRS-430.

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APPENDIX A

CLINICAL TEST CASES RECOMMENDED DURING COMMISSIONING

The clinical commissioning test cases are modeled to follow the procedures of the treatment

planning process. The anatomical tests are related to the creation of an anatomical model of

the patient for the following patients treatment planning. The dosimetric tests are designed to

cover a range of typical treatment techniques applied in the clinical practice. The CIRS

002LFC phantom is used to demonstrate the procedure. It was mentioned that the user canapply any phantom that is compliant to the requirements of IAEA Technical Reports Series

No. 430 [1]: however, the tests conditions and selection of measurement points should be

adjusted to the geometry of the selected phantom, see Appendix C. The set-up of each test is

described below. A set of instructions for performing each test is also included. If necessary,

additional hints for performing the set-up and the measurements are given. The calculations

are performed for each available algorithm. The grid size used in clinical practice shall be

employed.

For the evaluation of the measured (Dmeas)and RTPS calculated (Dcal) values the criteria that

were specified in TRS-430 are employed. However, due to the limited number of available

positions for dose measurements in the CIRS phantom, dose differences are normalized to the

dose measured at the reference point for each test case.

The following equation should to be used:

Error [%] =100*(Dcal-Dmeas)/Dmeas,ref (A.1)

where Dmeas, ref is the dose value measured at the reference point. This reference point is

specified for each test case. For multiple beam combination the difference between measured

and calculated dose values for selected beam should be related to the dose measured at the

reference point for the corresponded beam. For example, the difference between measured

and calculated dose values for anterior beam should be related to the dose measured at thereference point for the anterior beam. The agreement criteria for each case are given in

corresponding tables of this Appendix.

A.1 Anatomical and input test cases

Case 1: Verification of digitized contour non-dosimetric test

The purpose of this test is to verify the contouring capabilities of the RTPS. Two comparisons

should be done:

Digitize the master copy of the CIRS 002LFC Front view transverse cross-section contourusing the available digitizer and compare the digitized contour with the master copy.

Create contours of the CIRS 002LFC phantom from CT images using appropriate imagecontrast level and window and compare the master copy of the CIRS 002LFC Front

view transverse cross-section contour with the contour produced from the CT image.

Do this contouring manually and automatically, if possible.Compare distances A (AP diameter), B (LL diameter), C (RL diameter of hole #10), D (height

of lung cross-section through the centres of holes #6 & #7), and E (width of lung cross-

section at the level of the centre of hole #5), as indicated in figure A.1. The results of the

comparison should be written into Table A.1. The deviation should be about 1-2 mm

depending on the windowing used in the image for contouring.

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Table A.1. Comparison of contour dimensions.

Measured distancesType of the

contour

A B C D E

Master copy

DigitizedCT image

Figure A.1. Specification of distances used for comparison.

Case 2: Verification/determination of CT numbers to relative electron density conversion

used by RTPS

The purpose of this test is to determine and, if needed to adjust the CT numbers to RED

conversion curve stored in the RTPS. The CIRS 002LFC phantom should be scanned in the

available CT scanner (Fig. A.2) with the following parameters: HEAD FIRST SUPINE

(considering as HEAD the phantom film section), use the kV, Field of View, CT image

reconstruction kernel, slice thickness and spacing as usually applied in the department for a

typical thoracic scanning protocol. The labeling of holes and recommended arrangement of

the certified electron density reference plugs for the CT scan is given in Figure A.3.

B

A

10 C

6

7

5

D

E

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Figure A.2. Set-up of CIRS 002LFC phantom during CT scanning.

Figure A.3. Labelling of holes and the recommended arrangement of the certified electron densityreference plugs for the CT scan: Plug 1-water equivalent, plug 2- muscle substitute, plug 3 - syringefilled with water, plug 4 - adipose substitute, plug 5 - water equivalent, plug 6 - lung substitute, plug 7- should be empty to represent air, plugs 8 & 9 - lung substitutes, plug 10- bone substitute.

For each selected inhomogeneity, water and air, the CT numbers should be averaged over a

fixed area (the diameter of averaged region of interest should be close to 0.5 radius of the

insert). The region of interest for which the CT numbers are averaged should not be close to

the edge of the selected area. The averaged values should be compared to the CT numbers

used in the CT numbers to RED conversion curve stored in the RTPS. Agreement within 0.02is acceptable for REDs, i.e. CT numbers for a given object should not vary by more than +/-

20 CT numbers. If a significant change to CT numbers is observed and cannot be eliminated

by recalibration of the CT scanner, new CT numbers to RED data need to be entered into the

RTPS. If CT data are input using film, geometric checks for scaling and distortion are

necessary. Distortion may arise from either the CT filming process or the digitization process.

Produce a film of the test phantom, making sure that the image contrast (level and window)

are as before. Input the film in the usual way (e.g., CCD camera or digital scanner). If film

digitization is used for inhomogeneity corrections, bulk densities are usually assigned

manually (listed in Table 1). If the RTPS automatically maps the digital matrix to densities,

check that the densities are correct. As an example, Figure A.4 represents the CT numbers to

RED conversion results based on the CT scans with the CIRS 002LFC phantom performed atdifferent hospitals. It can be seen that the use of different CT scanners shows differences

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especially in the region with densities above that for water. The magnitude of the error in

calculated dose due to this difference may be approximately 2% for a 6 MV photon beam

passing through a thickness of 5 cm of the material with the RED of 1.5 (800 CT numbers).

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

-1200 -1000 -800 -600 -400 -200 0 200 400 600 800 1000 1200

Hounsfield units

Relative

electron

density

Institution 1

Institution 2

Institution 3

Institution 4

Institution 5

Institution 6

Figure A.4. CT calibration curves measured with CIRS phantom at different hospitals.

A.2. Dosimetric test cases

Case 1: Testing for reference conditions based on CT data

The purpose of this test is to verify the calculation for the reference field. A 10 cm x 10 cm

field with a gantry angle of 0 and collimator angle of 0 is used to confirm the basic beam

data. The measurement points are defined in the middle of holes 1, 3, 5, 9 and 10: see

Figure A.3 and Table A.2.

Table A.2 Geometry for case 1

Case Number

of beams

Set-up Reference

point

Measurement

point

Field Size [cm]

L x W

Gantry

angle

Collimator

angle

Beam

modifiers

1 1 SSD=SAD100 cm(linac)80 cm

(Co-60)

3 1359

10

10x10 0 0 none

Instructions for Case 1:

(1) Perform the treatment plan with the RTPS according to Table A.2 and document it.(2) Calculate with RTPS MU/time needed to deliver 2 Gy to the reference point #3.(3) Report the computed dose at points 1, 5, 9 and 10.(4) Perform manual MU/time calculation and compare result with RTPS MU/time

calculated values.

(5) Set up the phantom on the couch of the treatment machine with Head first supinetowards gantry.

(6) Align the phantom with lasers intersection at the centre of hole #5.(7) Set gantry angle to 0.(8) Set SSD=100 cm (80 cm for C0-60 or nominal SSD).(9) Set collimator rotation to 0.(10) Set field size: Length (Y) = 10 cm Width (X) = 10 cm

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(11) Insert ionisation chamber into the tissue plug and place it into hole #3.(12) Irradiate the phantom with the RTPS calculated MU/time.(13) Register the value of the measured doses. Repeat irradiation at least three times and

determine average value.

(14) Change the position of the ionisation chamber to the next hole #5.(15) Repeat steps 12 and 13 after changing the position of the chamber.(16) Change the position of the ionisation chamber to the next hole #1.(17) Repeat steps 12 and 13 after changing the position of the chamber.(18) Insert ionisation chamber into the bone-equivalent plug and place it into hole #10.(19) Repeat steps 12 and 13 after changing the position of the chamber.(20) Insert ionisation chamber into the lung-equivalent plug and place it into hole #9.(21) Repeat steps 12 and 13 after changing the position of the chamber.(22) Fill in Table A.3 with calculated and measured data and compare results.If several algorithms are available for dose calculations provide comparison of calculated and

measured values for each algorithm used. An example of the calculated dose distribution is

given in Figure A.5.

Table A.3. Comparison of measured and calculated data for case 1

Case Location of

measuring

point

Calculated dose

[Gy]

Measured dose

[Gy]

Deviation

[%]

Agreement criterion

[%]

1 2

3 2

5 2

9 4

1

10 3

Figure A.5. A sample dose distribution in central plane for case 1.

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Case 2: Oblique incidence, lack of scattering and tangential fields

The purpose of this test is to verify calculations in case of lack of scattering for the tangential

field. A 15 cm x 10 cm field with a gantry angle of 90 and collimator angle depending on the

wedge orientation is used. The isocentre and measurement point is defined in the middle of

hole #1: see Figure A.3 and Table A.4.

Table A.4. Geometry for case 2

Case Number

of

beams

Set-up Reference

point

Measurement

point

Field

Size [cm]

L x W

Gantry

angle

Collimator

angle

Beam modifiers

2 1 SAD 1 1 15x10 RL 90 0 or basedon wedge

orientation

45 degree wedge orthe largest wedge

angle available


(1) Perform the treatment plan with the RTPS according to Table A.4 and document it.(2) Calculate with RTPS MU/time needed to deliver 2 Gy to the reference point #1.(3) Perform manual MU/time calculation and compare the result with RTPS MU/time

calculated values.


(5) Align the phantom with lasers intersecting at the centre of hole #5.(6) Set gantry angle to 0, lower the couch to SSD =97 cm. for a 100 cm SAD machine(7) Set collimator rotation to 0 (collimator angle may be changed due to the conditions of

wedge orientation).

(8) Set field size: Length (Y) = 15 cm; Width (X) = 10 cm (wedged direction)(9) Move gantry to 90.(10) Insert the wedge, if needed rotate collimator.(11) Insert ionisation chamber into the tissue plug and place it into hole #1.(12) Irradiate the phantom with the RTPS calculated MU/time.(13) Register the value of the measured dose. Repeat irradiation at least three times and


(14) Fill in Table A.5 with calculated and measured data and compare results.If several algorithms are available for dose calculations provide comparison of calculated andmeasured values for each algorithm used. An example of a calculated dose distribution is



Case Location of

measuring

point

Calculated dose

[Gy]

Measured dose

[Gy]

Deviation

[%]

Agreement criterion

[%]

2 1 3

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Figure A.6. A sample dose distribution in central plane for case 2.

Case 3: Significant blocking of the field corners

The purpose of this test is to verify the calculation for the blocked field. Use a 14 cm x 14 cm

field with a collimator angle of 45 blocked to a 10 cm x 10 cm field with standard blocks or

with the MLC. The measurement point is defined in the middle of hole #3: see Figure A.3 and

Table A.6.


Case Number

of beams

Set-up Reference

point

Measurement

point

Field

Size [cm]

L x W

Gantry

angle

Collimator

angle

Beam

modifiers

3 1 SSD=SAD 3 3 14x14shaped

to10x10

0 45 Blocksor MLC


(1) Perform the treatment plan with the RTPS according to Table A.6 and document it.(2) Calculate with RTPS MU/time needed to deliver 2 Gy to the reference point #3.(3) Perform manual MU/time calculation compare result with RTPS MU/time calculated

values.


(5) Align the phantom with lasers intersection at the centre of hole #5.(6) Set gantry angle to 0.(7) Set SSD=100 cm (80 cm for C0-60 or nominal SAD).(8) Set collimator rotation to 45.(9) Set field size: Length (Y) = 14 cm Width (X) = 14 cm(10) Block the field corners to 10 cm x 10 cm. (figure A.9)(11) Insert ionisation chamber into the tissue plug and place it into hole #3.

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Case 4: Four field box

This technique is used in many radiotherapy hospitals and the purpose of this test is to verify

the calculation of the dose delivered with an individual beam and the total dose from four

fields. The four fields are weighted equally and the parameters and measurement points are

defined in the middle of holes 5, 6 and 10: see Table A.8 and Figure A.3. In each

measurement point the difference between measured and calculated dose for the selected

beam should be related to the dose measured at the reference point for the corresponded beam(for example: the difference between measured and calculated dose for anterior beam should

be related to the dose measured at the reference point for the anterior beam).

Table A.8. Geometry for test case 4

Case Number of

beams

Set-up Reference

point

Measurement

point

Field

Size [cm]

L x W

Gantry

angle

Collimator

Angle

Beam

modifiers

4 4 SAD 5 5610

15x10 Ant15x10 Post15x8 RL

15x8 LL

0180270

90

000

0

none


(1) Perform the treatment plan with the RTPS according to Table A.8 and document it.(2) Calculate with RTPS MU/time needed to deliver 2 Gy to the reference point #5.(3) Report the computed dose at points #6 and #10.(4) Perform manual MU/time calculation for each field and compare the results with

RTPS MU/time calculated values.


(6) Align the phantom with lasers intersecting at the centre of hole #5.(7) Set gantry angle to 0.(8) Set collimator rotation to 0.(9) Set field size: Length (Y) = 15 cm Width (X) = 10 cm(10) Insert ionisation chamber into the tissue plug and place it into hole #5.(11) Irradiate the phantom with the RTPS calculated MU/time for anterior field only.(12) Register the value of the measured dose. Repeat irradiation at least three times and


(13) Rotate gantry to 180.(14) Irradiate the phantom with the RTPS calculated MU/time for the posterior field.(15) Register the value of the measured dose. Repeat irradiation at least three times and

determine average value.(16) Rotate gantry to 90.(17) Set field size: Length (Y) = 15 cm Width (X) = 8 cm(18) Irradiate the phantom with the RTPS calculated MU/time for this field only.(19) Register the value of the measured dose. Repeat irradiation at least three times and


(20) Rotate gantry to 270.(21) Irradiate the phantom with the RTPS calculated MU/time for this field only.(22) Register the value of the measured dose. Repeat irradiation at least three times and


(23) Repeat steps 7 to 22 (except step 10) with the ionization chamber placed in hole #6.(24) Repeat steps 7 to 22 (except step 10) with the ionization chamber placed in hole #10.(25) Fill in Table A.9 with calculated and measured data and compare results.

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If several algorithms are available for dose calculations provide comparison of calculated and

measured values for each algorithm used. An example of the calculated dose distribution is


Figure A.9. A sample distribution in the central plane for case 4.


Case Location of

measuringpoint

Calculated

dose [Gy]

Measured dose

[Gy]

Deviation

[%]

Agreement

Criterion[%]

F1: 0 2

F2: 90 3

F3: 270 3

F4: 180 35

F1: 0 4

F2: 90 3

F3: 270 3

F4: 180 4

6

F1: 0 3

F2: 90 4

F3: 270 4

F4: 180 3

4

10

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Case 5: Automatic expansion and customized blocking

The purpose of this test is to verify auto-aperture function of RTPS and customized blocking

as well as the calculations with lung inhomogeneity. A cylinder of 8 cm diameter and 8 cm

long centered in point #2 should be expanded with a margin of 1 cm in all directions using the

expansion tools available. An MLC or block to conform to expanded volume should be

applied. The measurement point is defined in the middle of the hole 7: see Figure A.3 andTable A.10.


Case Number of

beams

Set-up Reference

point

Measurement

point

Field

Size [cm]

L x W

Gantry

angle

Collimator

angle

Beam

modifiers

5 1 SAD 2 2

7

defined

by block

or MLC

0 45 Custom

block or

MLC


(1) Perform the treatment plan with the RTPS according to Table A.10 and document it.(2) Calculate with RTPS MU/time needed to deliver 2 Gy to the reference point #2.(3) Report the computed dose at point #7.(4) Perform manual MU/time calculation and compare the result with RTPS MU/time

calculated value.


(6) Align the phantom with lasers intersecting at the centre of hole #5.(7) Set gantry angle to 0.(8) Move the table 4 cm laterally and 3 cm down (isocentre at hole #2).(9) Set collimator rotation to 0.(10) Insert custom block or conform MLC (whether applicable) and set the field size.(11) Insert ionisation chamber into the tissue plug and place it into hole #2.(12) Irradiate the phantom with the RTPS calculated MU/time.(13) Register the value of the measured dose. Repeat irradiation at least three times and


(14) Insert ionisation chamber into the lung equivalent plug and place it into hole #7.(15) Follow steps 10-11.(16) Fill in Table A.11 with calculated and measured data and compare results.If several algorithms are available for dose calculations provide comparison of calculated and

measured values for each algorithm used. An example of the calculated dose distribution and

BEV is given in Figures A.10 and A.11.


Case Location of

measuring

point

Calculated dose

[Gy]

Measured dose

[Gy]

Deviation

[%]

Agreement criterion

[%]

2 25

7 4

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Figure A.10. A Sample dose distribution in central plane for case 5.

Figure A.11. A sample BEV for case 5.

Case 6: Oblique incidence with irregular field and blocking the centre of the field

The purpose of this test is to verify the calculations for irregular fields with the blocking of

the center of the field. The isocentre should be set in the centre of the hole #5. A 20 cm x 10

cm field with gantry angle of 45 and collimator angle of 90 is used. An L-shaped field

should be created by blocking off a 6 cm x 12 cm field using custom block or MLC. The

parameters and measurement points are defined in the middle of holes 3 (reference point), 7,

and 10: see Table A.12 and Figure A.3.

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Table A.12 Geometry for case 6

Case Number

of

beams

Set-up Reference

point

Measurement

point

Field

Size [cm]

L x W

Gantry

angle

Collimator

Angle

Beam

modifiers

6 1 SAD 3 3

7

10

L-shaped

10x20

45 90 Customblock or

MLC


(1) Perform the treatment plan with the RTPS according to Table A.12 and document it.(2) Calculate with RTPS MU/time needed to deliver 2 Gy to the reference point #3.(3) Report the computed dose at points #7 and #10.(4) Perform manual MU/time calculation and compare the result with RTPS MU/time

calculated value.


(6) Align the phantom with lasers intersecting at the centre of hole #5.(7) Set gantry angle to 45.(8) Set collimator rotation to 90.(9) Set field size: Length (Y) = 10 cm Width (X) = 20 cm(10) Insert ionisation chamber into the tissue plug and place it into hole #3.(11) Insert custom block or shape the field with the MLC.(12) Irradiate the phantom with the RTPS calculated MU/time.(13) Register the value of the measured dose. Repeat irradiation at least three times and


(14) Insert ionisation chamber into the lung equivalent plug and place it into hole #7.(15) Repeat steps 12 and 13 after changing the position of the chamber.(16) Insert ionisation chamber into the bone equivalent plug and place it into hole #10.(17) Repeat steps 12 and 13 after changing the position of the chamber.(18) Fill in Table A.13 with calculated and measured data and compare results.If several algorithms are available for dose calculations provide comparison of calculated and

measured values for each algorithm used. An example of the calculated dose distribution and

BEV is given in Figures A.12 and A.13.

Table A.13 Comparison of measured and calculated data for case 6

Case Location ofmeasuring

point

Calculated dose[Gy]

Measured dose[Gy]

Deviation[%]

Agreement criterion[%]

6 3

7

10

3

4

5

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Figure A.12. A sample distribution in the central plane for case 6.

Figure A.13. A sample BEV for case 6.

Case 7: Three fields, two wedge-paired, asymmetric collimation

The purpose of this test is to verify the calculations with wedge-paired fields and

asymmetric collimation (if asymmetric collimators are not available use half-beam block).

The isocentre should be set in the centre of the hole #3. All fields are equally weighted.

Collimator angle should be set depending on the wedge insertions. The parameters and

measurement point are defined in the middle of the hole #5: see Table A.14 and Figure A.3.

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Table A.14 Geometry for test case 7

Case Number

of

beams

Set up Reference

point

Measurement

point

Field

Size [cm]

L x W

Gantry

angle

Collimator

angle

Beam modifiers

7 3 SAD 5 5 10x12

10x6 assym

10x6 assym

0

90

270

0

According

to wedgeorientation

None

Physical wedge 30

Soft wedge 30


(1) Perform the treatment plan with the RTPS according to Table A.14 and document it.(2) Calculate with RTPS MU/time needed to deliver 2 Gy to the reference point #5.(3) Perform manual MU/time calculation for each field and compare the results with

RTPS MU/time calculated values.


(5) Align the phantom with lasers intersecting at the centre of hole #5.(6) Set gantry angle to 0.(7) Set collimator rotation to 0.(8) Lower table 3 cm down (isocentre at hole #3).(9) Set field size: Length (Y) = 10 cm Width (X) = 12 cm(10) Insert ionisation chamber into the tissue plug and place it into hole #5.(11) Irradiate the phantom with the RTPS calculated MU/time for anterior field.(12) Register the value of the measured dose. Repeat irradiation at least three times and


(13) Rotate gantry to 90.(14) Set collimator rotation angle to provide proper wedge orientation.(15)

Set field size: Length (Y) = 10 cm Width (X1) = 0, Width (X2) = 6cm (those who donot have asymmetric jaws use on this field half beam block and set the field size to

10cm x 12 cm)

(16) Insert 30 physical wedge (see figure A.14).(17) Irradiate the phantom with the RTPS calculated MU/time for LL field.(18) Register the value of the measured dose. Repeat irradiation at least three times and


(19) Rotate gantry to 270.(20) Set collimator rotation angle to provide proper soft wedge orientation. (See figure

A.14). In case you have no soft wedge, repeat insertion of 30 physical wedge.

(21) Irradiate the phantom with the RTPS calculated MU/time for RL field.(22) Register the value of the measured dose. Repeat irradiation at least three times anddetermine average value.(23) Fill in Table A.15 with calculated and measured data and compare results.If several algorithms are available for dose calculations provide calculated values for each

algorithm used. An example of the calculated dose distribution is given in Figure A.14.

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Table A.15 Comparison of measured and calculated data for case 7

Case Location of

measuring

point

Calculated

dose [Gy]

Measured

dose [Gy]

Deviation

[%]

Agreement

criterion [%]

F1: 0 2

F1: 904

F1: 270 4

7

5

Figure A.14. A sample dose distribution in the central plane for case 7.

Case 8: Non coplanar beams with couch and collimator rotation

The purpose of this test is to verify the calculations with couch and collimator rotation.

Three fields with different gantry angles and collimator rotations are equally weighted. The

isocentre should be set in the centre of the hole #5. The parameters and measurement point

are defined in the middle of the hole #5: see Table A.16 and Figure A.3.

Table A.16. Geometry for test case #8

Case Number

of

beams

Set-up Reference

point

Measurement

point

Field

Size [cm]

L x W

Gantry

angle

Collimator

angle

Beam

modifiers

8 3 SAD 5 5 4x16 LL

4x16 RL

4x4 (table 270)

90

270

30

330

30

0

None

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(1) Perform the treatment plan with the RTPS according to Table A.16 and document it.(2) Calculate with RTPS MU/time needed to deliver 2 Gy to the reference point #5.(3) Perform manual MU calculation for each field and compare the results with RTPS

MU/time calculated values.


(5) Align the phantom with lasers intersecting at the centre of hole #5.(6) Set gantry angle to 90.(7) Set collimator rotation to 330.(8) Set field size: Length (Y) = 4 cm Width (X) = 16 cm(9) Insert ionisation chamber into the tissue plug and place it into the hole #5.(10) Irradiate the phantom with the RTPS calculated MU/time for LL field.(11) Register the value of the measured dose. Repeat irradiation at least three times and


(12) Set gantry angle to 270.(13)

Set collimator rotation to 30.(14) Irradiate the phantom with the RTPS calculated MU/time for RL field.

(15) Register the value of the measured dose. Repeat irradiation at least three times anddetermine average value.

(16) Set gantry angle to 30.(17) Set collimator rotation to 0.(18) Rotate table isocentrically to 270.(19) Set field size: Length (Y) = 4 cm Width (X) = 4 cm(20) Irradiate the phantom with the RTPS calculated MU/time for non coplanar field.(21) Register the value of the measured dose. Repeat irradiation at least three times and


(22) Fill in Table A.17 with calculated and measured data and compare results.If several algorithms are available for dose calculations provide calculated values for each

algorithm used. An example of the calculated dose distribution is given in Figure A.15.

Table A.17. Comparison of measured and calculated data for test 8

Case Location of

measuring

point

Calculated

dose [Gy]

Measured

dose [Gy]

Deviation

[%]

Agreement

criterion [%]

F1: 90 3F1: 270 3

F1: 30 3

8

5

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Figure A.15. A sample dose distribution in the central plane for case 8.

A.2.Summary of clinical commissioning testing

The tests, location of measuring points and agreement criteria for each point are summarized

in Table A.18. The user may utilize this table to document the results of the clinical

commissioning for future reference.

Table A.18. Form to document summary of clinical commissioning results (reference points

for each test case are marked with asterisk).

DescriptionCase

No.

Meas.

Point/Field

Agreement

criteria (%)

Users

difference

1 2

3*)

2

5 2

9 4

Testing for reference field based on CT data;test corresponds to photon test 1and MU test 1in TRS 430

1

10 3

Oblique incidence, lack of scattering andtangential fields; test corresponds to photon

tests 7, 10 and MU test 2 in TRS 430.

2 1*) 3

Significant blocking of the field corners; testcorresponds to photon tests 1, 3 and MU test 4in TRS 430.

3 3*)

3

F1: 0 2

F2: 90 3F3: 270 3

F4: 180 3

5*)

F1: 0 4

F2: 90 3

F3: 270 4

Four field box; test corresponds to clinical test

1 in TRS 430.

4

6

F4: 180 3

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DescriptionCase

No.

Meas.

Point/Field

Agreement

criteria (%)

Users

difference

F1: 0 3

F2: 90 4F3: 270 3

F4: 180 4

10

2*) 3Automatic expansion and customizedblocking; test combines test conditions related

to beam test 8, photon test 13, MU test 6, andclinical test 4 as described in TRS 430.

5

7 4

3*)

3

7 5

Oblique incidence with irregular field andblocking the centre of the field;

test corresponds to MU test 4 as described nTRS 430.

6

10 5F1: 0 2

F2: 90 4F3: 270 4

Three fields, two wedge-paired, asymmetric

collimation; test corresponds to MU test 3and clinical test 3 a described in TRS 430.

7 5*)

F1: 0 3

F2: 90 3

F3: 270 3

Non coplanar beams with couch and collimatorrotation; test corresponds to beam tests 6, 12and clinical test 6 in TRS 430.

8 5*)

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APPENDIX B

RESULTS OF PILOT STUDY

Introduction

The clinical commissioning procedures described in the current report were tested by the

participants of the Coordinated Research Project E2.40.13 to verify practicability of the tests,

selection of measurements points in the phantom and the needed amount of time to performthe measurements for each test. All participants used the same phantom and employed

ionization chamber dosimetry. A total number of 14 algorithms from 9 different RTPSs

brands installed in 18 hospitals were tested. The calculated and measured doses are compared

for all algorithms using exactly the same treatment plans and data points. The algorithms are

listed in Table B.1 according to the manufacturers description. The third column of Table

B.1 lists the energies used. The results of pilot study are given in Table B.2 and show the

range of deviations for each test, for each measurement point and for each algorithm. The

columns min and max contain the minimum and maximum dose deviations observed for

all energies tested for the specific algorithm (refer Table B.1). Following the RTPS manuals

the hospital users may identify the algorithms and inhomogeneity correction methods for their

RTPS and compare the results of their commissioning tests to the data for the selectedalgorithm presented in the report. The user may also consult AAPM Report 85 [4] for more

detailed information on algorithms used in RTPSs.

Algorithms A3, A4 and A5, labeled as pencil beam convolution with inhomogeneity

corrections based on equivalent TAR method implemented differently in RTPSs used. The

same is related to algorithms A7, A9, labeled as pencil beam convolution (kernel scaling with

depth). Figure B.1 shows the percentage of measurements with results outside the criteria of

agreement as a function of algorithm used and photon beam energy.

Table B.1. Dose computation algorithms

Algorithm identifier Algorithm description Beam energies

A1 Effective pathlength 6, 15 MV

A2 Clarkson (effective pathlength) Co-60, 6,10,15 MV

A3 Pencil beam convolution:

Equivalent TAR method

6, 15 MV

A4* Pencil beam convolution:


6, 10, 20 MV

A5* Pencil beam convolution:


6 MV


Modified Batho power law

method

4, 6, 10, 18, 20 MV

A7* Pencil beam convolution

(kernel scaling with depth)

6, 10, 15 MV

Implementation in different RTPSs

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Algorithm identifier Algorithm description Beam energies


TAR and 3D SAR integration

6 MV

A9* Pencil beam convolution

(kernel scaling with depth)

6 MV

A10 FFT (convolution kernels

not scaled but beam hardening

taken into account)

Co-60, 6, 10, 15 MV

A11 Anisotropic Analytical

Algorithm

4, 6, 18 MV

A12 Multi-grid superposition Co-60, 6, 10, 15 MV

A13 Collapsed cone point kernel

with 3D scaling

6, 15 MV

A14 Collapsed cone

convolution / superposition

6 MV

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A1

A2

A3

A4

A5

A6

A7

A8

A9

A

10

A

11

A12

A1

3

A14

Co-60

4 MV

6 MV

10 MV15 MV

18 MV20 MV

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

Percentageofmeasurements

with

resultsoutsideagreementcriteria

Figure B.1. The percentage of measurements with results outside agreement criteria as a

function of algorithm and photon beam energy.

The practicality of these clinical commissioning procedures has been studied through trial use

in several facilities and the measurements were performed on different treatment machines.

Table B.3 provides time estimates for treatment units with and without record and verify

(R&V) system with automatic set-up option. The hospital user can consult the data for

treatment machines to estimate the time needed to perform the measurements at his/herfacility.

Table B.3. Time estimate needed to perform measurements of clinical commissioning tests.

Test case No. Minimum time estimate ( minutes)

with automatic set-up without automatic set-up

1 20 25

2 15 20

3 10 15

4 (all fields) 40 80

5 15 20

6 15 20



TOTAL: 150 240

The time required to perform the whole chain of activities: phantom assembly and set-up, CT

scanning, planning, measurements and analysis would be approximately 16 hours (2 working

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days) for dual energy machine. The estimated machine time required: CT scanner about 30

min; RTPS about 5 hours; treatment machine about 5 hours.

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APPENDIX C

COMPARISON OF DIFFERENT PHANTOMS FOR

CLINICAL COMMISSIONING OF RTPS FOLLOWING AN IAEA PROTOCOL

Introduction

The IAEA recommendations include clinical commissioning test cases that cover typical

treatment techniques used in majority of radiotherapy hospitals. The test cases were designedto cover the widest possible range of the test case scenarios described in TRS-430. A phantom

that simulates the thorax including lung and bone inhomogeneities is best suited to support the

clinical commissioning tests. The shape of the thorax phantom will allow simulating an

oblique surface and have the possibility to include dosimeters inside volumes with lung or

bone equivalent materials. A solid phantom will have limitations in the number of possible

measurement points for ionization chambers. Therefore the number and the location of the

measuring points in the phantom are important. The RTPS clinical commissioning testing

should be as easy and accurate to perform as possible. Therefore the set up and handling of

the phantom should not be fault-prone or time-consuming. Several phantoms were evaluated

in terms of their suitability to support the tests described in the current report.

Phantoms

Five different multi-purpose phantoms commercially available at the time of the project have

been selected for comparison study: Model 002LFC (Computerized Imaging Reference

Systems), EasyBody (Euromechanics Medical GmbH), Quasar (Modus Medical Devices

Inc.), phantom 91235 (Standard Imaging Inc.), TomoTherapy cheese phantom (Gammex

RMI). Brief description of each phantom is given below.

The phantom Model 002LFC from Computerized Imaging Reference Systems Inc., (CIRS),

Norfolk, Virginia, USA was described in details in section 2.3.1 and shown in Figure 1.

The EasyBody phantom was developed by Euromechanics Medical GmbH, Schwarzenbruck,

Germany in cooperation with the University Medical Center Hamburg-Eppendorf, Germany.

It consists of the basic cubic phantom EasyCube and two expanders to form an abdominal

shaped phantom. The material is solid water (RW3) and the dimensions are 36 cm 18 cm

18 cm. The phantom consists of several solid water plates that can be replaced by the plates

made of bone or lung-equivalent material to create an anthropomorphical arrangement (see

Figure C.1). Ionization chamber holders, made of RW3, can be placed at nearly any position

in the phantom due to the plate structure. Films can be placed between every pair of plates

and also special plates with cutouts are available for better fixation of the film. A grid with 1

cm steps is marked on the phantom to be used for alignment purposes. A set of four certifiedelectron density plugs (lung, adipose, muscle and bone) can be inserted in the phantom for CT

calibration. An additional hollow plug can be filled with water and used as a reference.

The Quasar phantom is a product from Modus Medical Devices Inc., London, Ontario,

Canada. It is made of solid acrylic and has a size of 30 cm 12 cm 20 cm (see Figure C.2).

It is elliptically shaped and has three openings (diameter 8 cm) for cylindrical acrylic or low

density wood inserts (lung-equivalent). A film cassette can also be included in these openings

or even an adaptor to simulate respiratory motion. Six smaller openings (diameter 2cm) for a

bone equivalent rod or acrylic ionization chamber holder can be used. Several alignment

markers are located on the phantom.

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Figure C.1. The phantom Euromechanics GmbH, EasyBody.

An additional adaptor with five certified electron densities (lung inhale, polyethylene, water

equivalent, inner bone and dense bone) in a fixed arrangement is available for CT calibration

purposes.

Figure C.2. The phantom Quasar, Modus medical devices Inc.

The 91235 phantom from Standard Imaging Inc., Middelton, Wisconsin, USA consists of six

plates each of 3 cm thickness and dimensions of 30 cm 45 cmwhich can be stacked and

fixed with pins to reach a height of 18 cm(see Figure C.3). The set up mimics a human torso.

The main material is virtual water. Two plates have an inclusion of lung-equivalent material;

the other four plates are solid apart from the holes (1 cm diameter) in all six plates where

ionization chamber holders made of virtual water can be inserted. A solid rod made of bone

equivalent material also fits in these cavities. Markers on the phantom allow an easy

alignment. Films can be included between any pair of plates. No CT calibration is possible

with this phantom because no certified density materials are available.

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Figure C.4. The Standard imaging phantom 91235.

The TomoTherapy cheese phantom is a solid water phantom that was manufactured by

Gammex RMI, Middleton, Wisconsin, USA for verification purposes of the TomoTherapy

machines (see figure C.4). It is cylindrical in shape, its dimensions are 30 cm () 18 cm

and has 20 holes of 2.8 cmdiameter in which 12 different plugs of certified electron densities

can be included for CT calibration. All other holes can be filled with solid water plugs. Also

ionization chamber holder made of solid water can be included in these openings. For dose

verification purposes the phantom can not be expanded or filled with inhomogeneities to

mimic a human torso. The phantom consists of two semi-cylindrical halves, in between which

a film can be included. Metallic markers are placed on the surface for alignment purposes.

Figure C.4. The phantom Gammex RMI, TomoTherapy cheese phantom.

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Parameters evaluated

The suitability of each phantom for clinical commissioning was investigated. This includes

checking whether a CT calibration is possible, the possible anthropomorphic set-ups of the

phantoms, the investigation of the materials and the possibilities for dose verifications. The

possibility of an anthropomorphic set-up is necessary to check DRRs and inner contours. The

existence of alignment markers and error-proneness of the alignment and set up process werealso examined. All phantoms with certified electron densities were set up for CT scanning. As

an example Figure C.5 shows one CT slice for each phantom. Based on the results of CT

scanning a CT number/RED conversion table was determined for each phantom.

Three clinical commissioning test cases described in the current document (cases 1, 2 and 6 -

Appendix A) were performed for all five phantoms. An anthropomorphic setup for each

phantom was created where it was possible. Figures C.5 shows the corresponding CT images

of the phantoms that were scanned for treatment planning.

Figure C.5. CT mages of CIRS Inc model 002LFC (left) and Euromechanics GmbH EasyBody (right)phantoms used for clinical commissioning tests.

Figure C.6. CT mages of Standard Imaging 91235(left) and Gammex RMI TomoTherapy Cheese

(right) phantoms used for clinical commissioning tests.

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Figure C.7. CT mage of Modus Medical Quasar phantom used for clinical commissioning tests.

Table C.1. Characteristics of the studied phantoms

Manufacturer CIRS Inc EUROMECHANICSMEDICAL GmbH

MODUSMEDICALDEVICES

Inc

STANDARDIMAGING

Inc

GAMMEXRMI

Phantom/feature 002LFC Easybody Quasar 91235 TomotherapyCheese

Dimensions(W x L x H) cm

30x30x20 36x18x18 30x12x20 30x45x18 30x18

Shape Thorax Abdominal Thorax Thorax Cylinder

Body material Solid water RW3 Acrylic Virtual water Solid waterIon chamber

locations

10

(inside tissue,lung, bode)

Several - depending

on plates structure(inside tissue, lung,

bone)

6

(inside tissue,lung, bone)

16

(inside tissue)

20

(inside tissue)

Film placement(plane)

Transversal Transversal,coronal, saggital

Transversal,coronal,

saggital

Coronal Coronal,saggital

Number ofcertified ED

plugs

5 4 5 none 12

Oblique

incidencemodelling

Yes Yes Yes Only for

tilted beams

Yes

Inhomogeneities Tissue,lung, bone

Tissue, lung(optional), bone

Tissue, lung(optional),

bone

Tissue, lung(optional),

bone

None

Alignmentmarkers

Metallicmarkers

Grid on surface Markers onsurface

Grid onsurface

Metallicmarkers

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Results

Anatomical tests and CT calibration

The TomoTherapy cheese phantom provides only verification of calculation for a

homogeneous volume. Therefore its testing was limited to CT calibration with use of flexible

arrangement of the 12 different calibrated materials. The possibilities for inserting ionizationchambers is sufficient as well as the possibility for film measurements were also evaluated.

The Standard Imaging phantom does not provide certified materials for CT calibration. An

inhomogeneous set-up is possible for dose verification measurements, but the plate structure

inhibits the use of a curved beam entry surface. The possibilities for placement of ionization

chamber and films for dose verification measurements are sufficient; however, measurements

in bone and lung are not possible.

The Modus Medical Quasar phantom allows measurements with an anthropomorphic set-up.

Ionization chamber measurements are possible in acrylic and lung volumes. Chamber holders

made of lung-equivalent material are not provided. Film measurements using the film cassette

are possible only in coronal and sagittal direction. As the phantom has no plate structure, thearea for film measurements is limited. A CT calibration is possible, but the adaptor with a

fixed arrangement of materials can not be mounted inside the phantom. The adaptors

dimensions are very small and it does not simulate a human body. This arrangement

influences the accuracy of the CT calibration.

The Euromechanics EasyBody can be used with an anthropomorphic arrangement.

Measurements with ionization chambers and films are possible, as this phantom is the most

flexible due to the plate structure. Measurements in bone and lung volumes are possible, but

ionization chamber holders are made only from RW3. A CT calibration is possible, but the

user has to select an appropriate arrangement.

The CIRS Model 002LFC provides one set-up for all tests. The number of measurement

points for ionization chambers is sufficient and the film measurements provide enough

information. The shape of the phantom is simulating human torso and a CT calibration is

possible. The phantom is the only one which provides ionization chamber holders made from

lung and bone-equivalent materials in order to perform measurements inside these materials.

CT calibration tests for all phantoms shows similar results (see Figure C.8). A slight influence

of the phantom size for dense materials can be seen. Due to the beam hardening and the

energy spectrum present at the location of the material, larger phantoms will lead to a smaller

CT value for a material. Therefore a realistic phantom shape similar to the human body is

necessary.

Clinical commissioning test cases

The clinical test cases 1, 2 and 6, described in details in Appendix A, were used to investigate

five phantoms with respect to their applicability for the clinical commissioning tests. The first

test case can be performed with all five phantoms. Measurement points at the central axis

(CAX) are possible for all phantoms; measurements in lung volume are possible for the CIRS

002LFC, the EasyBody and the Quasar phantoms. Only CIRS 002LFC and EasyBody

phantoms allow measurements in the spine area (bone inhomogeneity). The second test case

could not be performed for the Standard Imaging phantom as it has a flat surface and the

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tangential wedged field can not be placed in an adequate manner. For the other phantoms the

set-up with gantry angle of 90 could be realised and the use of a measurement point at the

central axis is possible. For the third test case different gantry angles were used for the

different phantoms. As the TomoTherapy cheese phantom does not include lung

inhomogeneity the phantom was not used for this test case. The Standard Imaging phantom

does not allow measurement in lung volume, nevertheless all other measurement points could

be used. Figure C.8 shows the four CT calibration curves obtained

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

-1000 -800 -600 -400 -200 0 200 400 600 800 1000 1200

CT numbers

relativeE

Modus medical, Quasar Euromechanics GmbH, EasyBody CIRS, Model 002LFC Gammex RMI, TomoTherapyCheese

Figure C.8. CT calibration curves. A slight influence of the phantom size can be seen for dense materials. Larger

phantoms lead to smaller CT values for the same material.

Summary

The phantoms differ with respect to their flexibility to be used for CT calibration and dose

verification.

TomoTherapy cheese phantom provides the largest possibilities for CT calibration, but due to

the lack of an anthropomorphic set-up, no testing of the inhomogeneity corrections for the

clinical test cases is possible

EasyBody provides the largest number of possible measurement points, but this flexibility

requires modifications of the whole set-up for CT calibration and then changing selection of

measurement points. This makes the set-up fault-prone and time consuming.

Standard Imagingphantom does not include certified electron densities and lacks sufficient

realistic shape for the investigated clinical commissioning tests.

Quasarphantoms` shape does not simulate well human body for CT calibration.

CIRSthorax phantom can support properly both the CT calibration and the test cases.

Recommendations

Only phantoms with an anthropomorphic geometry and removable plugs with certified

electron densities are able to support full scale clinical commissioning of a RTPS.

Anthropomorphic phantoms with sliced structure are suitable for film dosimetry

measurements in homogenous and inhomogenous regions.

Each phantom that was investigated in this study has advantages and disadvantages for the

specific tests. Clinical commissioning of RTPS that might be used in different hospitals

requires a phantom with minimal restricted flexibility and easy handling. On the other hand

the phantom must have the capability to perform all dosimetric and anatomical test cases. Thethorax phantom is the most suitable as it provides large volume inhomogeneities, curved

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surface and its large overall size allows accommodating large fields. Taking this into

consideration, the CIRS phantom Model 002LFC is preferable to support clinical

commissioning tests of RTPS.

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APPENDIX D

THE USE OF CLINICAL COMMISSIONING TEST RESULTS IN

PERIODIC QUALITY ASSURANCE OF RTPS

Introduction

The results of RTPS commissioning can be used as the reference data for the ongoing

periodic QA programme that covers checks of the integrity of hardware, software and datatransfer. General procedures for QC checks of RTPS are outlined in IAEA Technical Reports

Series No. 430 [1] together with a reference to a test designed to perform that check, and a

suggested frequency for the test. This section of the current report describes the

implementation of the results of clinical commissioning tests into the practice of periodic QA

for RTPS used in external radiotherapy treatment planning as recommended in TRS-430. It is

Commissioning for Radiotherapy TPS

Documents

Transcript of Commissioning for Radiotherapy TPS